High-strength green silver-saving alloy and preparation method thereof

Abstract

This invention discloses a high-strength, green, silver-saving alloy and its preparation method, comprising the following materials by mass percentage: 18-25% Ag, 45-55% Cu, 20-28% Zn, 0.5-1.5% Sn, 1.0-2.0% Ni, 0.1-0.3% P, and 0.1-0.5% rare earth elements; wherein the rare earth elements include Ce and / or La; the silver content is successfully reduced from the conventional 30% or more to below 25%, the raw material cost can be reduced by 15-30%, resulting in significant economic benefits and saving strategic precious metal resources. Furthermore, through the synergistic effect of quaternary microalloying of Sn, Ni, P, and Re (rare earth elements), solid solution strengthening, grain refinement strengthening, melt purification, and interface optimization are achieved, ensuring high strength and excellent processing plasticity of the alloy under the premise of low silver content, and avoiding performance degradation caused by silver reduction.

Description

Technical Field

[0001] This invention belongs to the field of metal materials technology, specifically referring to a high-strength, green, silver-saving alloy and its preparation method. Background Technology

[0002] Copper-silver alloys are widely used in electronics, hardware manufacturing, and integrated structural and functional components due to their excellent electrical and thermal conductivity, corrosion resistance, and mechanical properties. To ensure comprehensive performance, traditional copper-silver alloys typically contain more than 30% silver (Ag), with some high-end alloys reaching up to 50%. However, silver, as a scarce strategic precious metal, has a high price that significantly increases alloy production costs and leads to excessive consumption of precious metal resources, which is inconsistent with the industrial development needs of green, low-carbon, and resource-saving industries.

[0003] Existing technologies attempt to reduce the silver content in copper-silver alloys to save silver and reduce costs. However, simply reducing silver directly leads to an increase in the alloy's melting point, a decrease in mechanical strength, and a deterioration in plasticity. This makes the alloy prone to brittle cracking during processing, making it difficult to produce practical profiles such as foils, strips, and wires through rolling, drawing, and other processes. In addition, some traditional silver alloys have toxic and harmful elements such as cadmium (Cd) added to improve performance, which violates international environmental directives such as RoHS, resulting in insufficient green and environmentally friendly properties.

[0004] Currently disclosed silver-saving alloy technologies mostly employ the addition of single elements such as tin (Sn) and nickel (Ni) for modification, resulting in limited synergistic effects in alloying and an inability to simultaneously achieve high strength and good workability with low silver content. Furthermore, when using nanoparticles to enhance alloy properties, these particles are prone to agglomeration, making uniform dispersion within the alloy matrix difficult. This significantly reduces the strengthening effect and may even exacerbate material brittleness, becoming a core technical challenge hindering the development of high-performance silver-saving alloys. Therefore, developing a novel silver-saving alloy with a silver content below 25%, environmentally friendly, combining high strength and excellent workability, and capable of uniform dispersion of nanoparticles, has become a critical issue urgently needing to be addressed in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-strength, green, silver-saving alloy and its preparation method. Through the synergistic regulation of quaternary microalloying of Sn, Ni, P, and rare earth elements, combined with an innovative molten salt encapsulation nanocomposite process, the alloy achieves a balance of high strength, excellent processing plasticity, and environmental friendliness under the condition of silver content ≤25%. This solves the problems of performance degradation, nano-reinforcing particle agglomeration, and high processing brittleness in traditional silver-saving alloys after silver reduction.

[0006] According to the technical solution of the present invention, a high-strength, green, silver-saving alloy is provided, comprising the following materials by mass percentage: 18-25% Ag, 45-55% Cu, 20-28% Zn, 0.5-1.5% Sn, 1.0-2.0% Ni, 0.1-0.3% P and 0.1-0.5% rare earth elements; Rare earth elements include Ce and / or La.

[0007] Preferably, the material further includes 0.5-2.0% by mass of nano-reinforcing particles, wherein the nano-reinforcing particles are TiN particles or Al2O3 particles, and the particle size of the nano-reinforcing particles is 20-100 nm.

[0008] Preferably, the nano-reinforcing particles are uniformly coated on the surface of the alloy matrix particles to form a core-shell structured composite powder.

[0009] On the other hand, the present invention also provides a method for preparing the above-mentioned high-strength green silver-saving alloy, comprising the following steps: S1. Melting: Weigh the raw materials, place them in a melting furnace under vacuum or inert gas protection, heat them until completely melted and hold them at that temperature before casting them into alloy ingots; ultrasonic vibration is applied during the melting process; S2. Powder preparation: The alloy ingot is crushed, mechanically ground, or prepared into pre-alloyed powder with a particle size of less than 150 μm by gas atomization.

[0010] Furthermore, following S2, when the alloy contains nano-reinforcing particles, a composite step S2a is performed: The pre-alloyed powder was ball-milled with nano-reinforcing particles and a KCl-NaCl mixed salt at a mass ratio of 1:1, with a ball-to-material mass ratio of 5:1-10:1, a ball milling speed of 200-300 rpm, and a time of 2-4 h. The ball-milled mixture was then heated to 700-850℃ under an inert atmosphere and held for 1-2 hours to melt the KCl-NaCl mixed salt and coat the nano-reinforcing particles and alloy powder. After cooling to room temperature, it was washed, filtered and dried to obtain a core-shell structured composite powder coated with nano-reinforcing particles.

[0011] Furthermore, it also includes S3: The powder obtained from S2 or S2a is loaded into a mold and hot-pressed under a vacuum or argon atmosphere. The sintering temperature is 650-750℃, the pressure is 30-50MPa, and the holding time is 60-90min to obtain a densified alloy billet.

[0012] Furthermore, it also includes S4: The alloy billet is hot-rolled at 700-800℃, then warm-rolled at 400-500℃ with a cumulative deformation of not less than 70%, and processed into foil strips or wires. Then, it is stress-relief annealed at 300-400℃ for 30-60 minutes.

[0013] Furthermore, in S2a, the mass ratio of nano-reinforcing particles to pre-alloyed powder is (0.005-0.02):1.

[0014] Furthermore, S1 specifically refers to: Weigh the raw materials, place them in a melting furnace under vacuum or inert gas protection, heat them to 1150-1200℃ to completely melt them and hold them at that temperature for 10-30 minutes. Apply ultrasonic vibration at a frequency of 20-40kHz during the melting process, and then cast them into alloy ingots.

[0015] Beneficial effects: This invention successfully reduces the silver content from the conventional 30% or more to below 25%, which can reduce raw material costs by 15-30%, resulting in significant economic benefits and saving strategic precious metal resources. Furthermore, through the synergistic effect of quaternary microalloying of Sn, Ni, P, and Re (rare earth elements), solid solution strengthening, grain refinement, melt purification, and interface optimization are achieved, ensuring high alloy strength and excellent processing plasticity under the premise of low silver content, and avoiding performance degradation caused by silver reduction. This invention prepares core-shell composite powder using a molten salt encapsulation method, further solving the problem of nano-reinforcement particle agglomeration in raw materials. This allows the dispersion strengthening effect of nano-reinforcement to be fully utilized. The alloy does not contain toxic and harmful elements such as cadmium, meeting international environmental protection requirements. Through warm rolling / warm drawing and annealing processes, the alloy exhibits excellent plasticity and can be smoothly processed into foils, wires, and other profiles to meet various forming needs. Detailed Implementation

[0016] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection.

[0017] This invention provides a high-strength, green, silver-saving alloy comprising the following materials by mass percentage: 18-25% Ag, 45-55% Cu, 20-28% Zn, 0.5-1.5% Sn, 1.0-2.0% Ni, 0.1-0.3% P and 0.1-0.5% rare earth elements; Rare earth elements include Ce and / or La.

[0018] In a further embodiment of this example, the method further includes 0.5-2.0% by mass of nano-reinforcing particles, wherein the nano-reinforcing particles are TiN particles or Al2O3 particles, and the particle size of the nano-reinforcing particles is 20-100 nm.

[0019] In a further embodiment of this example, the nano-reinforcing particles are uniformly coated on the surface of the alloy matrix particles to form a core-shell structured composite powder.

[0020] On the other hand, embodiments of the present invention also provide a method for preparing the above-mentioned high-strength green silver-saving alloy, comprising the following steps: S1. Melting: Weigh the raw materials, place them in a melting furnace under vacuum or inert gas protection, heat them until completely melted and hold them at that temperature before casting them into alloy ingots; ultrasonic vibration is applied during the melting process; S2. Powder preparation: The alloy ingot is crushed, mechanically ground, or prepared into pre-alloyed powder with a particle size of less than 150 μm by gas atomization.

[0021] Furthermore, following S2, when the alloy contains nano-reinforcing particles, a composite step S2a is performed: The pre-alloyed powder was ball-milled with nano-reinforcing particles and a KCl-NaCl mixed salt at a mass ratio of 1:1, with a ball-to-material mass ratio of 5:1-10:1, a ball milling speed of 200-300 rpm, and a time of 2-4 h. The ball-milled mixture was then heated to 700-850℃ and held for 1-2 hours under an inert atmosphere to melt the KCl-NaCl mixed salt and coat the nano-reinforcing particles and alloy powder. After cooling, the mixture was washed and filtered to obtain a core-shell structured composite powder coated with nano-reinforcing particles.

[0022] In a further embodiment of this example, S3 is also included: The powder obtained from S2 or S2a is loaded into a mold and hot-pressed under a vacuum or argon atmosphere. The sintering temperature is 650-750℃, the pressure is 30-50MPa, and the holding time is 60-90min to obtain a densified alloy billet.

[0023] In a further embodiment of this example, S4 is also included: The alloy billet is hot-rolled at 700-800℃, then warm-rolled at 400-500℃ with a cumulative deformation of not less than 70%, and processed into foil strips or wires. Then, it is stress-relief annealed at 300-400℃ for 30-60 minutes.

[0024] In a further embodiment of this example, the mass ratio of nano-reinforcing particles to pre-alloyed powder in S2a is (0.005-0.02):1.

[0025] In a further embodiment of this example, S1 specifically refers to: Weigh the raw materials, place them in a melting furnace under vacuum or inert gas protection, heat them to 1150-1200℃ to completely melt them and hold them at that temperature for 10-30 minutes. Apply ultrasonic vibration at a frequency of 20-40kHz during the melting process, and then cast them into alloy ingots.

[0026] It should be noted that: The design principles and functional synergies of each component are as follows: Ag serves as the basic wetting and corrosion-resistant phase. Strictly controlling its content below 25% is crucial for achieving silver-saving and cost-reduction (silver saving rate > 20%). If the content is too low, basic processing performance cannot be guaranteed.

[0027] Cu and Zn form the main framework of the alloy. The Cu-Zn phase and the Ag-Cu eutectic phase together determine the basic melting point and strength of the alloy. Zn can effectively reduce melt and surface tension, but its content needs to be precisely controlled to prevent hot brittleness.

[0028] Sn, as a highly efficient melting point reducing element, can further lower the solid-liquid phase temperature of alloys and improve fluidity. Its content must be strictly controlled; excessive amounts will lead to severe segregation and processing brittleness.

[0029] Ni plays a key role in solid solution strengthening and grain refinement. Ni can significantly refine the brazing seam structure and improve the strength and heat resistance of the joint at room temperature and intermediate temperature.

[0030] As a powerful deoxidizer, phosphorus (P) can effectively remove oxygen from the alloy melt during the smelting process, purify the melt, and thus significantly improve the fluidity and spreading properties of the melt.

[0031] Re is added in the form of rare earth elements Ce and / or La. Rare earth elements have extremely strong "surface activity," which can significantly reduce the interfacial tension between the liquid and the base material (especially stainless steel and copper), greatly improving wetting and spreading ability. At the same time, rare earth elements can also refine grains and purify grain boundaries.

[0032] Nanoparticles, as second-phase dispersed strengthening particles, can effectively pin dislocations and grain boundaries, directly improving the strength and hardness of the alloy itself and the brazing seam after solidification, especially the performance retention rate at high temperatures.

[0033] The preferred preparation steps of the above-mentioned high-strength green silver-saving alloy preparation method are as follows: Melting: Accurately weigh high-purity silver, copper, zinc, tin, nickel, phosphorus copper alloy (as a source of phosphorus), rare earth elements, and other raw materials according to the alloy design proportions described above. Place the raw materials in a vacuum induction melting furnace or a medium-frequency induction melting furnace protected by a high-purity inert gas (such as argon with a purity ≥99.999%). Raise the furnace temperature to 1150-1200℃ to completely melt all the raw materials. Hold at this temperature for 10-30 minutes, and introduce ultrasonic vibration at a frequency of 20-40kHz during the melting process to ensure uniform alloy composition and preliminary grain refinement. Subsequently, pour the molten alloy liquid into a preheated water-cooled copper mold for rapid solidification to obtain a uniformly composed alloy ingot.

[0034] Powder preparation: The obtained alloy ingot is mechanically crushed and then ground using a ball mill, or prepared into pre-alloyed powder using a gas atomization method. The particle size of the pre-alloyed powder should be less than 150 micrometers, preferably with a D50 particle size between 50 and 100 micrometers.

[0035] Nano-reinforcement composite: This step is crucial for preparing high-performance composite powders. The pre-alloyed powder, nano-reinforcement particles (TiN or Al2O3), and a mixed salt (e.g., a 1:1 mass ratio of KCl to NaCl) as a dispersion medium are placed together in a planetary ball mill. The ball-to-powder mass ratio is controlled at 5:1 to 10:1, the milling speed is 200-300 rpm, and the milling time is 2-4 hours to ensure thorough mixing. Subsequently, the uniformly mixed material is transferred to a crucible and heated to 700-850℃ under flowing argon or nitrogen protection and held for 1-2 hours. At this temperature, the mixed salt (KCl-NaCl) melts to form a liquid salt, which encapsulates and isolates the nano-reinforcement particles, while the alloy powder remains solid or has a slightly molten surface. After cooling, the powder is repeatedly washed, filtered, and dried with deionized water at 60-80℃ to thoroughly remove the water-soluble mixed salt, finally obtaining a dry core-shell structured composite powder with nano-reinforcement particles uniformly coated on the surface of the alloy powder.

[0036] Molding: The pre-alloyed powder obtained in step 2 or the core-shell composite powder obtained in step 3 is loaded into a graphite or high-strength mold. The mold is placed in a hot-pressing sintering furnace and evacuated to 10°C. -2 After the pressure drops below 1 MPa, argon gas is introduced for protection. Under vacuum or argon atmosphere, hot-pressing sintering is performed at a pressure of 30-50 MPa and a temperature of 650-750 °C, with a holding time of 60-90 minutes. This process densifies the powder particles through diffusion bonding, resulting in a blocky alloy ingot with a density close to the theoretical density.

[0037] Plastic processing: The alloy ingot obtained from hot pressing and sintering undergoes plastic processing to produce a suitable product shape. First, the ingot is hot-rolled in a protective atmosphere (such as argon) at 700-800℃. Subsequently, it undergoes multiple warm rolling passes at 400-500℃, with a total cumulative deformation of not less than 70%, ultimately producing a foil strip with a thickness of 0.05-0.2 mm. Alternatively, the ingot can be drawn into wire with a diameter of 0.5-2.0 mm under similar temperature conditions. For alloys containing elements such as Sn, this warm rolling / warm drawing process is crucial to avoid cracking and ensure successful processing.

[0038] Post-processing: The processed foil strips or wires are subjected to stress-relief annealing at 300-400℃ for 30-60 minutes, followed by air cooling. Finally, an ultrasonic cleaner can be used with organic solvents such as acetone and ethanol to clean and dry the finished product, resulting in a smooth surface. This product can also be used as solder.

[0039] The present invention is further illustrated below through multiple embodiments and comparative examples, all of which are within the scope of protection defined in the claims. Performance testing adopts a unified standard for objective comparison.

[0040] Performance testing methods: To comprehensively evaluate performance, the following standardized tests were performed on the finished products (foil strips or wires) obtained from the examples and comparative examples: Electrical conductivity: In accordance with GB / T3048-2007 Test Method for Electrical Conductivity of Metallic Materials, the room temperature volume conductivity of the alloy was tested using an eddy current conductivity meter and characterized by the International Standard for Annealed Copper (%IACS). The test temperature was controlled at 25℃, and five different test points were selected for each sample. The average value was taken as the final result.

[0041] Mechanical properties: Brazing was performed on standard 304 stainless steel specimens (size: 100mm × 25mm × 2mm) with an overlap length of 3 times the plate thickness. After brazing, standard tensile specimens were machined, and the room temperature tensile strength (MPa) of the joint was measured on a universal testing machine. The average value of 5 specimens was taken for each data set.

[0042] Processing performance: Bend a 0.1mm thick foil strip around a mandrel with a diameter 10 times its thickness at 180° and observe whether it cracks; or bend a 1.0mm diameter wire repeatedly at 90° until it breaks and record the number of bends.

[0043] Microstructure: Prepare metallographic specimens of brazed joints and observe the microstructure morphology, composition distribution, and presence of defects (such as cracks and pores) of the brazed joint under a scanning electron microscope (SEM).

[0044] Example 1 Alloy composition (wt%): 22% Ag, 50% Cu, 24.2% Zn, 1.0% Sn, 1.5% Ni, 0.2% P and 0.5% Ce.

[0045] Preparation method: Melting: According to the alloy design proportions described above, accurately weigh high-purity silver, copper, zinc, tin, nickel, phosphorus copper alloy (as a source of phosphorus), rare earth elements, and other raw materials. Place the raw materials in a vacuum induction melting furnace. Raise the furnace temperature to 1180℃ to completely melt all raw materials. Hold at this temperature for 20 minutes, and introduce ultrasonic vibration at a frequency of 30kHz during the melting process to ensure uniform alloy composition and preliminary grain refinement. Subsequently, pour the molten alloy into a preheated water-cooled copper mold, and rapidly solidify to obtain a uniformly composed alloy ingot.

[0046] Powder preparation: The obtained alloy ingot is mechanically crushed and then ground using a ball mill, or prepared into pre-alloyed powder using a gas atomization method. The particle size of the pre-alloyed powder is 80 micrometers.

[0047] Molding: The obtained pre-alloyed powder is loaded into a graphite or high-strength mold. The mold is placed in a hot-pressing sintering furnace and evacuated to 10°C. -2 After the pressure drops below 40 MPa, argon gas is introduced for protection. Under vacuum or argon atmosphere, hot-pressing sintering is performed at 40 MPa and 680 °C, with a holding time of 60 min. This process densifies the powder particles through diffusion bonding, resulting in a blocky alloy ingot with near-theoretical density.

[0048] Plastic processing: The alloy billet obtained by hot pressing and sintering is plastically processed to form a suitable product shape. First, the billet is hot rolled in an argon protective atmosphere at 750°C. Then, it is subjected to multiple warm rolling at 450°C, with a total cumulative deformation of not less than 70%, and finally processed into a foil strip with a thickness of 0.1 mm.

[0049] Post-processing: The processed foil strips or wires are subjected to stress-relief annealing at 350℃ for 40 minutes, followed by air cooling. Finally, the finished product is cleaned and dried using an ultrasonic cleaner with organic solvents such as acetone and ethanol to obtain a smooth final product.

[0050] Example 2 Alloy composition (wt%): 22% Ag, 50% Cu, 23.7% Zn, 1.0% Sn, 1.5% Ni, 0.2% P, 0.5% Ce and 1.0% nano TiN.

[0051] Preparation method: The difference from Example 1 is that a nano-reinforcement composite step is added between powder preparation and molding: The pre-alloyed powder, TiN nanoparticles as reinforcement, and KCl-NaCl (mass ratio 1:1) as a dispersion medium were placed together in a planetary ball mill. The ball-to-particle mass ratio was controlled at 10:1, the milling speed at 250 rpm, and the milling time at 3 hours to ensure thorough mixing. The uniformly mixed material was then transferred to a crucible and heated to 800°C and held for 1 hour under flowing argon or nitrogen protection. At this temperature, the mixed salt (KCl-NaCl) melted to form a liquid molten salt, which encapsulated and isolated the nanoparticles, while the alloy powder remained solid or had a slightly molten surface. After cooling, the powder was repeatedly washed and filtered with 70°C deionized water to completely remove the water-soluble mixed salt, ultimately yielding a dry core-shell structured composite powder with nanoparticles uniformly coated on the surface of the alloy powder.

[0052] Example 3 Alloy composition (wt%): 18% Ag, 55% Cu, 23.1% Zn, 1.2% Sn, 1.5% Ni, 0.2% P and 0.5% La.

[0053] Preparation method: The difference from Example 1 is as follows: Molding: The obtained pre-alloyed powder is loaded into a graphite or high-strength mold. The mold is placed in a hot-pressing sintering furnace and evacuated to 10°C. -2 After the pressure drops below 40 MPa, argon gas is introduced for protection. Under vacuum or argon atmosphere, hot-pressing sintering is performed at 700°C and a pressure of 40 MPa for 60 minutes. This process densifies the powder particles through diffusion bonding, resulting in a blocky alloy ingot with a density close to the theoretical density.

[0054] Example 4 Alloy composition (wt%): 25% Ag, 45% Cu, 25.2% Zn, 0.8% Sn, 2.0% Ni, 0.3% P and 0.2% Ce.

[0055] Preparation method: Same as in Example 1.

[0056] Example 5 Alloy composition (wt%): 20% Ag, 52% Cu, 24.3% Zn, 0.5% Sn, 1.0% Ni, 0.1% P, 0.1% Ce and 2.0% nano Al2O3.

[0057] Preparation method: Same as in Example 2, except that nano-TiN is replaced with nano-Al2O3.

[0058] Example 6 Alloy composition (wt%): 21% Ag, 48% Cu, 26.4% Zn, 1.5% Sn, 1.5% Ni, 0.3% P, 0.25% Ce and 0.25% La.

[0059] Preparation method: Same as Example 1.

[0060] Example 7 Alloy composition (wt%): 23% Ag, 47% Cu, 25.5% Zn, 0.5% Sn, 2.0% Ni, 0.2% P and 0.3% Ce.

[0061] Preparation method: Same as Example 1.

[0062] Example 8 Alloy composition (wt%): 24% Ag, 46% Cu, 27.8% Zn, 0.5% Sn, 1.0% Ni, 0.2% P and 0.3% La.

[0063] Preparation method: Same as Example 1.

[0064] Comparative Example 1 BAg30CuZnSn copper-silver alloy.

[0065] Comparative Example 2 Alloy composition (wt%): 22% Ag, 50% Cu, 26.8% Zn, 1.0% Sn and 1.5% Ni.

[0066] Preparation method: Same as in Example 1.

[0067] Comparative Example 3 Alloy composition (wt%): 30% Ag, 36% Cu, 29.7% Zn, 4% Sn and 0.3% nano TiN.

[0068] Preparation method: Nano-TiN is mechanically stirred and mixed with atomized alloy powder, and then hot-pressed and rolled in the same manner as in Example 1.

[0069] The test results of the above embodiments and comparative examples are shown in Table 1 below: Table 1

[0070] It can be seen from Table 1 above: The tensile strength of the alloys in the embodiments of this invention is all >340MPa, which is significantly higher than that of Comparative Example 1 (traditional high-silver alloy) and Comparative Example 2 (P-deficient and rare-earth-deficient); the nano-reinforcement (TiN / Al2O3) can further improve the strength by 10%-15% through dispersion strengthening, and the hardness is improved simultaneously.

[0071] Through the synergistic regulation of quaternary microalloying of Sn, Ni, P and rare earth elements, combined with warm rolling process, the alloy can achieve 180° bending without cracking, and the wire can be bent more than 8 times, completely solving the industry problem of high brittleness and easy cracking of low silver alloys.

[0072] The molten salt encapsulation method solves the problem of nano-reinforcement particle agglomeration from the root, resulting in refined alloy grains, clean grain boundaries, and uniform phase distribution. In contrast, Comparative Example 2, which lacks P and rare earth elements, exhibits structural defects due to insufficient deoxidation and grain boundary contamination. In contrast, Comparative Example 3, which uses traditional mechanical mixing, shows severe agglomeration of nano-reinforcement particles, which becomes a source of stress concentration.

[0073] Example 4 (Ag content 25%, the upper limit of this invention) had an electrical conductivity of 68±1% IACS, the highest among all samples, indicating that Ag content is the core element for regulating the conductivity of the alloy, and increasing the Ag content within the silver-saving range can significantly optimize conductivity.

[0074] In Examples 2 and 5, after the addition of nano-reinforcement, the conductivity decreased slightly by 2-3% IACS compared to the sample with the same composition without nano-reinforcement particles. This is because the nano-reinforcement particles are an insulating phase, and a small amount of dispersed distribution will slightly hinder electron transport, but the decrease is extremely small and can be ignored.

[0075] Example 6 uses Ce+La composite rare earth, with an electrical conductivity of 66±2% IACS. Rare earth elements can purify grain boundaries, reduce impurity scattering, and compensate for the slight negative impact of single rare earth on conductivity.

[0076] The conductivity of all embodiments remained stable at 62-68% IACS, meeting the requirements for use in electronic appliances and conductive structural components.

[0077] Comparative Example 1 (Traditional 30% Ag high silver alloy): The electrical conductivity is only 60±3% IACS, which is lower than all examples. This is because there is no P or rare earth deoxidation purification, and there are elemental segregation and impurities inside the alloy, which greatly increases electron scattering.

[0078] Comparative Example 2 (P-deficient and rare earth-deficient): The conductivity was only 52±4% IACS, the lowest among all samples. The lack of P element led to molten oxide inclusions, and the lack of rare earth elements caused grain boundary contamination. The dual defects led to a sharp deterioration in conductivity.

[0079] Comparative Example 3 (mechanical mixing of nano-reinforcing particles): conductivity 55±3%IACS, nano-TiN is severely agglomerated to form a bulk insulating phase, blocking the electron conduction path, and the conductivity is much lower than that of the core-shell structure composite sample of the present invention.

[0080] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength, green, silver-saving alloy, characterized in that, Includes the following percentages of material by mass: 18-25% Ag, 45-55% Cu, 20-28% Zn, 0.5-1.5% Sn, 1.0-2.0% Ni, 0.1-0.3% P and 0.1-0.5% rare earth elements; Rare earth elements include Ce and / or La.

2. The high-strength, green, silver-saving alloy according to claim 1, characterized in that, It also includes 0.5-2.0% by mass of nano-reinforcing particles, wherein the nano-reinforcing particles are TiN particles or Al2O3 particles, and the particle size of the nano-reinforcing particles is 20-100 nm.

3. The high-strength, green, silver-saving alloy according to claim 2, characterized in that, The nano-reinforcing particles are uniformly coated on the surface of the alloy matrix particles to form a core-shell structured composite powder.

4. A method for preparing a high-strength, green, silver-saving alloy according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Melting: Weigh the raw materials, place them in a melting furnace under vacuum or inert gas protection, heat them until completely melted and hold them at that temperature before casting them into alloy ingots; ultrasonic vibration is applied during the melting process; S2. Powder preparation: The alloy ingot is crushed, mechanically ground, or prepared into pre-alloyed powder with a particle size of less than 150 μm by gas atomization.

5. The preparation method according to claim 4, characterized in that, The process also includes, after S2, performing a composite step S2a when the alloy contains nano-reinforcing particles: The pre-alloyed powder was ball-milled with nano-reinforcing particles and a KCl-NaCl mixed salt at a mass ratio of 1:1, with a ball-to-material mass ratio of 5:1-10:1, a ball milling speed of 200-300 rpm, and a time of 2-4 h. The ball-milled mixture was then heated to 700-850℃ and held for 1-2 hours under an inert atmosphere to melt the KCl-NaCl mixed salt and coat the nano-reinforcing particles and alloy powder. After cooling, the mixture was washed and filtered to obtain a core-shell structured composite powder coated with nano-reinforcing particles.

6. The preparation method according to claim 5, characterized in that, Also includes S3: The powder obtained from S2 or S2a is loaded into a mold and hot-pressed under a vacuum or argon atmosphere. The sintering temperature is 650-750℃, the pressure is 30-50MPa, and the holding time is 60-90min to obtain a densified alloy billet.

7. The preparation method according to claim 6, characterized in that, Also includes S4: The alloy billet is hot-rolled at 700-800℃, then warm-rolled at 400-500℃ with a cumulative deformation of not less than 70%, and processed into foil strips or wires. Then, it is stress-relief annealed at 300-400℃ for 30-60 minutes.

8. The preparation method according to claim 5, characterized in that, In S2a, the mass ratio of nano-reinforcing particles to pre-alloyed powder is (0.005-0.02):

1.

9. The preparation method according to claim 5, characterized in that, Specifically, S1 is: Weigh the raw materials, place them in a melting furnace under vacuum or inert gas protection, heat them to 1150-1200℃ to completely melt them and hold them at that temperature for 10-30 minutes. Apply ultrasonic vibration at a frequency of 20-40kHz during the melting process, and then cast them into alloy ingots.

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